1. Field of the Invention
The present invention relates to a dew sensor, and more specifically to an improvement in the structure of a dew sensor.
2. Description of the Prior Art
Dew sensors having a resistance value which decreases with an increase of humidity (that is, dew sensors showing a negative humidity-resistance characteristic) are known. Examples of such dew sensors are dew sensors using a thick film in which conductive powder and dew sensors semiconductor powder is dispersed, or using ceramics which mainly contains titanium complex oxide as a humidity sensitive member.
Although detecting electrodes are generally used for detecting variations in resistance value, it is common to structure the humidity sensitive device such that the humidity sensitive member is formed to cover all of top surface of detecting electrodes. More specifically, the humidity sensitive member is formed to cover entirely a pair of electrodes, for example, a pair of parallel electrodes or a pair of comb-shaped electrodes, as detecting electrodes. U.S. Pat. No. 4,263,576, issued Apr. 21, 1981 discloses dew sensors as described above.